In recent years, biodegradable resins, for example, polylactic acid (PLA) have come into focus from the viewpoint of environmental preservation. PLA is biodegradable thermoplastic aliphatic polyester, derived from renewable resources, such as corn starch or sugarcanes. PLA is a rigid and highly transparent biodegradable resin.
However, PLA has an insufficient gas barrier property for use as a material for fluid storage containers such as food storage containers. PLA has insufficient mechanical properties in some applications, e.g. packaging, due to its rigidity. Finally, PLA has too, insufficient thermal resistance for hot filling or transportation of bottles during the summer months. Hot filling is one of the methods that beverage makers use to reduce the chances pathogens end up in their products. The hot-filling process involves filling containers immediately after the product has been sterilized through a thermal processing operation at high temperature.
Therefore, PLA has limitations in its applications. In order to modify the gas barrier, thermal resistance and mechanical properties of PLA, the incorporation of nano-scale silicate by dispersion in the polymer matrix is a good solution.
Nanocomposites are sometimes prepared today using organically modified silicates produced by a cation exchange reaction between the silicate and usually an alkylammonium salt.
Preparation of modified phyllosilicates is well known. Thus, under appropriate conditions an organic compound containing a cation that can react by ion exchange with a phyllosilicate containing a negative layer lattice and exchangeable cations does so react to form the modified phyllosilicate.
The patent application EP1787918 describes a biodegradable polyester resin reinforced by a phyllosilicate. The phyllosilicate is substituted with ammonium, pyridinium, imidazolium, or phosphonium ions. Examples of ammonium ions include tetraethylammonium, octadecyltrimethylammonium, and dimethyldioctadecylammonium among other ions. The resin has improved barrier properties but no consideration is given regarding improvements in the mechanical properties such as the elongation at break.
Thus, from what is known, it is derived that the development of a material with improved mechanical, thermal and barrier properties is still of great interest.